1. Description of the Invention
The present invention relates to an apparatus for driving a vehicle door such as a back vehicle door to open and close by driving a motor, in other words, a switching apparatus for opening and closing an open-close structure such as the back door vehicle.
The present application is based on Japanese Patent Applications No. Hei. 11-234566 and 11-310366 which are incorporated herein by reference.
2. Description of the Related Art
There exists an apparatus for driving a back door of a station wagon, or a switching apparatus for opening and closing the back door by driving a motor as disclosed in Japanese Utility Model Publication No. Hei. 6-71852, for example.
In the switching apparatus above, the roof of the vehicle body is equipped with a motor, a reduction mechanism provided in parallel to the motor, a segment gear engaging with the pinion gear of the reduction mechanism and rockingly pivotally connected thereto in the horizontal direction to form a transmission member, and a linearly-reciprocating rod pivotally connected to a part separated from the rotational center of the segment gear to form a coupling member. In this case, the rear end portion of the rod is pivotally connected to the vertically opening-closing door so that the door can be opened and closed by rocking the segment gear to move the rod back and forth.
In the conventional apparatus for driving a vehicle door to open and close, however, it is necessary to secure a great deal of space for use in providing the rod in the vehicular roof because the segment gear is moved along the roof surface so as to linearly rock the rod back and forth. Consequently, the problem lies in the fact that the interior room space needs decreasing in consideration of head clearance intended for anyone sitting in the rear seat.
Further, in the conventional switching apparatus, a ball joint is used for coupling the front end portion of the rod to the segment gear so that the rod can vertically tilt round the front end portion thereof coupled to the segment gear as the door opens or closes. Consequently, the way of coupling the rod to the segment gear tends to become complicated and this will result in an increase in costs.